Due to demand for smaller and thinner electronic devices, a heating element, such as an electronic part installed in an electronic device, is densely installed in a small space, and due to high sealingness of the electronic device, electronic parts installed inside the electronic device are readily exposed to heat. Once electronic parts are exposed to heat for a long time, their performance may be degraded and lifetimes thereof are also shortened.
The problems described above can be addressed by using, typically, a heat dissipating device that emits heat to the outside to reduce an amount of heat affecting electronic parts. As a material for the heat dissipating device, metal, graphite, carbon, or the like may be used. However, these materials may not be directly connected to electronic devices due to their strength and limitations on a molded shape.
As an alternative to the heat dissipating device, a thermally conductive material may be used as a material for electronic parts. As the thermally conductive material, metal may be used. However, a metal material has low productivity and has poor moldability due to its limitation on part design. Also the metal material is inappropriate for manufacturing lightweight electronic devices.
Accordingly, a study for a thermally conductive polymer that is injection-moldable and due to this property, provides high productivity and enables a precise design has been carried out. However, because the thermally conductive polymer typically has a thermal conductivity of 0.5 W/mK or less, it is impossible to use the thermally conductive polymer itself as an alternative to metal.
Accordingly, recently, a polymer composite material that includes an additive for increasing the thermal conductivity has been studied. For example, KR 2009-0041081 discloses a thermally conductive resin composite material including polyphenylene sulfide (PPS) as a crystalline polymer resin, a mixed metal filler, and a low melting point metal. However, if an amount of the PPS exceeds 85 vol % in the thermally conductive resin composite material, flowability of PPS is decreased and thus an injection molding process thereof is difficult to be performed. Also, PPS is not smoothly mixed with other elements and it is difficult to secure a predetermined level or more of thermal conductivity which is appropriate for actual use environments requiring the thermal conductivity. Also, if an amount of the PPS is less than 30 vol. % in the thermally conductive resin composite material, it is difficult to manufacture a composite material itself. The thermal conductive resin composite material has a thermal conductivity of 3.5 W/mK or less even under optimal conditions. Thus, this thermal conductivity level is lower than 10 W/mK, a level at which a thermally conductive polymer material can replace metal.
Thus, up to now, only metal materials are used as a material for electronic parts requiring high thermal conductivity